Infectious disease watchers were worried in the late summer of 2013. The largest annual mass gathering in the world, the Hajj, was approaching. Meanwhile, infections with the new MERS coronavirus were mounting weekly in Saudi Arabia, where more than two million of the Muslim faithful would soon gather.

The fear was the event would give the new virus wings – a round-the-world ticket to wherever returning pilgrims might travel. It was easy to imagine MERS taking root in the slums of south Asia or Africa, fuelling outbreaks in overcrowded hospitals in some of the world’s mega-cities. In other words, becoming the next SARS.

It didn’t happen.

In fact, when experts studying this disease reflect on MERS in 2013 and prognosticate on how the disease’s story will play out in 2014, the non-event of the Hajj is a source of marvel – and relief.

“Probably the biggest surprise in 2013 for me is that the epidemic didn’t come from the Northwestern Hemisphere,” says Dr. Christian Drosten, a coronavirus expert who runs the University of Bonn’s institute of virology.

“I’m really very surprised that it has not left the region.”

In fact, the virus has made a few faltering forays beyond the Arabian Peninsula, where all known chains of transmission started and all individual cases occurred.

A few infected people from the region have been transported by air ambulance to hospitals in Europe. A French tourist brought the virus home from the United Arab Emirates. A Tunisian man returning from Qatar infected two of his children. And yes, two residents of Spain who attended the Hajj caught the virus, though it’s not clear if they were infected during the pilgrimage.

But the lack of any real post-Hajj outbreaks and the passage of time have lowered alarm levels on MERS, a number of the experts who have been heavily involved in researching the new disease acknowledge.

“I have really the growing feeling that it’s not very contagious,” says Drosten, whose personal level of concern was considerably higher earlier in 2013.

The World Health Organization’s top MERS expert, Dr. Anthony Mounts, also admits to a lessening of tensions about the virus.

“Time has shown us that it’s not an explosive outbreak that’s going to spread from person to person outside of the region in an explosive way,” Mounts says.

“I can’t say ‘Never,’ but it hasn’t so far. It hasn’t shown that potential. So unless something changes with its behaviour, I think it’s going to continue to be a concern and a problem, but it’s certainly proving it doesn’t have the same capacity as SARS did to transmit.”

Infectious disease watchers were worried in the late summer of 2013. The largest annual mass gathering in the world, the Hajj, was approaching. Meanwhile, infections with the new MERS coronavirus were mounting weekly in Saudi Arabia, where more than two million of the Muslim faithful would soon gather.

The fear was the event would give the new virus wings – a round-the-world ticket to wherever returning pilgrims might travel. It was easy to imagine MERS taking root in the slums of south Asia or Africa, fuelling outbreaks in overcrowded hospitals in some of the world’s mega-cities. In other words, becoming the next SARS.

It didn’t happen.

In fact, when experts studying this disease reflect on MERS in 2013 and prognosticate on how the disease’s story will play out in 2014, the non-event of the Hajj is a source of marvel – and relief.

“Probably the biggest surprise in 2013 for me is that the epidemic didn’t come from the Northwestern Hemisphere,” says Dr. Christian Drosten, a coronavirus expert who runs the University of Bonn’s institute of virology.

“I’m really very surprised that it has not left the region.”

In fact, the virus has made a few faltering forays beyond the Arabian Peninsula, where all known chains of transmission started and all individual cases occurred.

A few infected people from the region have been transported by air ambulance to hospitals in Europe. A French tourist brought the virus home from the United Arab Emirates. A Tunisian man returning from Qatar infected two of his children. And yes, two residents of Spain who attended the Hajj caught the virus, though it’s not clear if they were infected during the pilgrimage.

But the lack of any real post-Hajj outbreaks and the passage of time have lowered alarm levels on MERS, a number of the experts who have been heavily involved in researching the new disease acknowledge.

“I have really the growing feeling that it’s not very contagious,” says Drosten, whose personal level of concern was considerably higher earlier in 2013.

The World Health Organization’s top MERS expert, Dr. Anthony Mounts, also admits to a lessening of tensions about the virus.

“Time has shown us that it’s not an explosive outbreak that’s going to spread from person to person outside of the region in an explosive way,” Mounts says.

“I can’t say ‘Never,’ but it hasn’t so far. It hasn’t shown that potential. So unless something changes with its behaviour, I think it’s going to continue to be a concern and a problem, but it’s certainly proving it doesn’t have the same capacity as SARS did to transmit.”